WASHINGTON Jan 4, 2007 (AP)— The FBI's file on former Chief Justice William Rehnquist made public more than a year after his death indicates the Nixon and Reagan administrations enlisted its help in blunting criticism of him during confirmation hearings.

The file also offers insight into the hallucinations and other symptoms of withdrawal that Rehnquist suffered when he was taken off a prescription painkiller in 1981. A doctor was cited as saying that Rehnquist, an associate justice of the Supreme Court at the time, tried to escape the hospital in his pajamas and imagined that the CIA was plotting against him.

The FBI on Wednesday released 1,561 pages of documents on Rehnquist to The Associated Press, other news organizations and scholars in response to requests made under the Freedom of Information Act following Rehnquist's death in September 2005. An additional 207 pages were withheld under the federal disclosure law, and the FBI said an entire section of his file could not be found.

Much of the FBI's file on Rehnquist appears to have been compiled almost exclusively for his two Senate confirmations his initial nomination to the court by President Nixon in 1971 and his nomination as chief justice by President Reagan in 1986. Administration officials apparently hoped to prevent any surprises from sinking his nominations.

In 1971, Deputy Attorney General Richard Kleindienst directed the FBI to conduct investigations of witnesses who were planning to testify at a Senate hearing against Rehnquist's confirmation. Fifteen years later during the Reagan administration, the FBI was enlisted to conduct background checks on witnesses who were scheduled to testify against Rehnquist's nomination to become chief justice.

The late Sen. Strom Thurmond, R-S.C., was chairman of the Senate Judiciary Committee in 1986 when Rehnquist was nominated to be chief justice. John Bolton, who resigned in December as President Bush's U.N. ambassador, was an assistant attorney general under Reagan.

"Thurmond just gave these names to Bolton they will testify for the Democrats and we want to know what they are going to say," a Justice Department official told a counterpart at the FBI, according to a memo in Rehnquist's file.

Alexander Charns, a Durham, N.C., lawyer who received the file and has extensively researched the FBI's relationship with the court, said the new disclosures show the two administrations went to some lengths to discredit Rehnquist opponents.

"In many ways, I guess it's the same old story of the political use of the FBI," Charns said.

The documents show that the FBI was aware in 1971 that Rehnquist had owned a home in Phoenix with a deed that allowed him to sell only to whites. The restrictive covenant was not disclosed until his 1986 confirmation hearings, at which Rehnquist said he became aware of the clause only days earlier.

Also detailed in the declassified file was Rehnquist's 1981 hospital stay for treatment of back pain and his dependence on powerful prescription pain-relief medication.

The FBI investigated his dependence on Placidyl, which Rehnquist had taken for at least 10 years, according to a summary of a 1970 medical examination.

When Rehnquist checked into a hospital in 1981 for a weeklong stay, doctors stopped administering the drug, causing what a hospital spokesman at the time said was a "disturbance in mental clarity."

The FBI file, citing one of his physicians, said Rehnquist experienced withdrawal symptoms that included trying to escape the facility and discerning changes in the patterns on the hospital curtains. The justice also thought he heard voices outside his room discussing various plots against him.

The doctor said Placidyl is a highly toxic drug and that she could not understand why anyone would prescribe it, especially for long periods.

Prior to his hospitalization, Rehnquist occasionally slurred his speech in his questions to lawyers at Supreme Court arguments. Those problems ceased when he changed medications, the doctor said.

Charns said some of the censored documents provide intriguing hints of what else Rehnquist's file might contain.

In one previously secret memo from 1971, an FBI official wrote, "No persons interviewed during our current or 1969 investigation furnished information bearing adversely on Rehnquist's morals or professional integrity; however …" The next third of the page is blacked out, under the disclosure law's exception for matters of national security.

"It would be nice to know what is still classified, three decades later," Charns said.